The present invention relates to a tool for holding one or more turbine blades during the application of a cathodic arc coating to the underplatform area of the turbine blade(s).
Jet engine turbine blades work in a difficult, corrosive environment and are subject to extremes of temperature. As a result, portions of the blade need to be coated to counter the effects of corrosion and heat such as pitting. One of those portions is the underplatform area of the turbine blade.
Cathodic arc coating and other techniques have been used to apply various coatings, such as platinum-aluminide coatings, to various turbine blade portions. However, conventional tooling to mask root and airfoil portions of the blade allowed too much coating to deposit on the tool itself. As a result, access to the underplatform areas to be coated became limited.
Thus, there is a need for improved tooling for use in the coating of underplatform areas of a turbine blade.
Accordingly, it is an object of the present invention to provide an improved tool for use in an underplatform coating operation.
It is a further object of the present invention to provide a tool as above which is compatible with standard cathodic arc coating apparatus.
It is yet a further object of the present invention to provide a tool as above which has specifically configured openings to allow coating deposition only in those underplatform areas where coating is required.
It is still a further object of the prevent invention to provide a tool as above which is easy to assemble and which can be used more than once.
The foregoing objects are attained by the tool of the present invention.
In accordance with the present invention, a tool for holding at least one turbine blade having a platform during the application of a coating to underplatform areas of the at least one turbine blade is provided. The tool comprises one or more fixtures for holding one or more turbine blades during the coating application. Each fixture comprises a base receptacle for receiving a turbine blade and a cover for the base receptacle. Each of the base receptacle and the cover have an opening which corresponds in shape to one of the underplatform areas to be coated. In one embodiment, the tool of the present invention has two fixtures joined together to permit simultaneous coating of the underplatform areas of two turbine blades.